Mercury-vapor device.



2SHEETS-SHEET 1 E. THOMSON.

MERCURY VAPOR DEVICE.

APPLICATION FILED JAN.21. 1911.

1,006,@05, Patented 001;. 24, 1911.

2 SHEETS-SHEET 2.

I nvnk ELIHU THOMSON, OF SWAMPSGOTT, MASSACHUSETTS,

' TRIO COMPANY, A CORPORATION OF ASSIGNOR T0. GENERAL ELEC- NEW YORK.

MERCURY-VAPOR DEVICE.

Specification of Letters Patent.

Application filed January 21, 1911.

Patented Oct. 24, 1911. Serial No. 603,897.

To all whom it may concern:

Be it known thatI, ELIHU 'THoMsoN, a citizen of the United States, residing at Swampscott, in the county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Mercury-Vapor specification.

The present invention relates to vapor electric devices, such as mercury arc lamps, and it comprises a device in which external fluid pressure acts directly upon the electrodes.

It is the object of my invention to provide a simple form of device, uncomplicated with vacuum seals, and which permits the establishment of an are under a definite pressure.

In the accompanying drawings, Figure 1 is a sectional view of one embodiment of my invention; Figs. 2 and 3 are detail views showing the electrode vessels and the tube connecting the same; Figs- 4 and 5 show modified forms of arc inclosing envelops; Figs. 6 and 7 illustrate electromagnetic devices for striking an arc, and Fig. 8 is a detail view of a valve containing piston for breaking the continuity of the mercury to start an arc.

Devices, of which the following is a are in a vacuum, the arc runs at a higher efficiency when it is at a pressure of one atmosphere or thereabout above atmospheric pressure, and heretofore this higher pressure has been obtained by the vaporization of the mercury itself when considerable amounts of'energy are delivered to the arc.

In accordance with the present invention,

the arc is started against a considerable external pressure which acts directly upon the mercury forming one or both of the electrodes.

Referring to Fig. 1, the U-shaped arc tube 1 is shown mounted within an outer inclosing envelop 2, consisting of glass and sealed so as to withstand pressure above atmospheric. The arc tube 1 preferably consists of quartz or highly refractory glass.

" The vertical legs of this tube enter vessels 3,3, each having an opening 4, 4 communicating with the space surrounding the tube serves to transfer the electrode to the other electrode,

1. The mercury within the arc tube communicates with the mercury in the vessels 3, 3, either through suitable openings, such as are illustrated at 5, 5, or through the open ends of the tube. The vessels 3, 3' are connected by a non-conducting tube 7, as-

shown more clearly in Fig. 2. This tube globules of mercury con'densmg in the neighborhood of the cooler thereby maintaining the proper level of mercury. The connecting tube 7 rises slightly at the center as shown in Fig. 3, thereby causing the mercury when flowing from one elec trode chamber to the other to break up into v separate, or discrete, particles, without short circuiting the electrodes. tions are made to the electrodes by means Current connecof wires 8, 9 sealed into the walls of vessels 3, 3' and connected to binding posts 10, 11, which pass through the base 12 of the lamp and, if necessary, are suitably insulated therefrom as indicated. External connections are made to these binding posts ithrough suitable steadying resistances 13,

which may be in the nature of ballast resistances, that. is, increasing rapidly in value beyond a certain current value. Although it is usual to operate a mercury The inclosing globe 2 is clamped to the base 12, making an air-tight gasketed joint therewith, as indicated in the drawing. It I is surrounded by a strong wire netting 14.

A tube 15, communicating with the interior of the envelop 2, provides means for filling the same with compressed air or other gases at a pressure of about one atmosphere.

As is indicated in the drawing, the U- tube is slightly contracted at its upper part 6 so that the mercury lies in a thin layer in this region. A slight amount of gas may be left in the arc tube in order to decrease the cross section of the mercury at this contracted regi0n,or the pressure of the gas surrounding the U-tube before starting may i be slightly less than that corresponding with the pressure of the mercury column in the tubes. In either case, when current is impressed upon the mercury electrodes, the arc starts by vaporization of the mercury at the contracted region, and the heat of the are vaporizes more mercury, thereby generating enough pressure to drive the mercury down each leg of the tube against the external gaseous pressure. If the are has been started against a low external pressure as mdlcated above, this external pressure is increased gradually until the full density of the arc is attained.

It will be observed that the mercury electrodes are in communication through the mercury standing in the chambers 3,3 with the gaseous pressure within the outer inclosing globe 2. The pressure of the gas outside and inside the arc tube 1 is therefore equal, disregarding the weight of the short mercury columns still remaining in the U- tube, and the arc may be operated under considerable pressure and at high current density. The lam is therefore not only simple, inasmuch as 11: does not require vacuum tight leading-in conductors, but it may also be run at high efiiciency at considerable pressure.

The shape of the arc tube 1 may bevaried 1 at will in order to obtain greater lengths.

Alternative forms of arc tube are illustrated in Figs. 4 and 5, the former showing the tube twisted around itself in a sort of open double helix and the latter illustrating a form in which the straight leg has the other leg as an outer spiral or helix passing around it at a small distance.

Instead of starting the tube by the vaporization of mercury at the contracted portion as described in connection with Fig. 1, it may be started by breaking the mercury column by exerting a sudden downward jerk upon the mercury. Fig. 6 shows a U-tube provided at its lower ends with cylinders 16, 17, in which pistons 18, 19 are loosely fitted. These pistons are connected to rods 20, 21, which consist of non-conducting material, or else are properly insulated from each other. These rods are connected to the armature 22 of the electromagnet 23. The pistons are loosely fitted in the cylinder so that the mercury may pass from the U-tube and the cylinders l6, 17 to the outer chambers 24:, 25,-

but, when a sudden jerk is exerted upon the pistons by the pull of the electromagnet, they will act to separate the mercury at the contracted portion 26 of the U-tube, thereby striking the arc.

It is not necessary for the starting of the lamp in the manner above described to provide a piston for each leg of the U-tube. Fig. 7 illustrates an alternative form of the device in which a piston is provided for one leg only, the other leg being closed except for a small opening which allows the mercury within the U-tube 1 to pass into the outer chamber 25. The piston in the cylinder 16 of the lower end of the other leg is controlled in the manner as already described in connection with Fig. 6 by an electromagnet 23, the piston rod being connected to the armature of the magnet by lever 26 as indicated.

Instead of fitting the piston loosely within the cylinder and depending upon the leakage of the mercury past the cylinder in order to permit the lengthening of the are within the U-tube, the piston may be provided with a downwardly opening valve as illustrated in Fig. 8. The structure shown in this figure will be understood without any detailed description, the pressure of the mercury upon the upper side of the cylinder simply forcing downward the ball 27 which is springpressed against the opening in the cylinder.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In a vapor electric device, the combination of a closed receptacle containing a fluid under pressure, an envelop located within said container, cooperating electrodes, one of which consists of mercury in said envelop, current connections therefor, and means for transmitting the fluid pressure to said electrodes.

2. In a vapor electric device, the combination of a closed receptacle containing a gas under pressure, an open envelop within said container, cooperating electrodes therein, at least one of which consists of a liquid, current connections, and means for transmitting the external gaseous pressure to said liquid electrode.

3. In a vapor electric device, the combination of a closed receptacle containing a fluid under pressure, an envelop situated within said receptacle and communicating therewith, a vaporizable cathode and a cooperating anode in said envelop, current connections therefor, and means for separating said electrodes thereby striking an arc.

4. The combination of a hermetically sealed receptacle filled with a gas under pressure, an open-ended refractory envelop situated therein, a body ofmercury in said envelop, current connections therefor, and mechanical means for breaking the continuity of said mercury body, thereby striking'an are.

5. The combination of a hermetically sealed receptacle, filled with a gas under pressure,

an open-ended refractory envelop situated therein, a body of mercury in said envelop,

currentconnections therefor, a piston sliding in the open ends of said envelop, and means for suddenly movin said piston, thereby breaking the continuity of the mercury body and striking the arc.

6. In a vapor electric device, the combination of a closed receptacle containing a gas under pressure, an open-ended envelop situated therein containing a body of mercury, separate mercury containing reservoirs communicating with each of the open ends of said inner envelop, appropriate current coni In witness whereof, I have hereunto set nections to said body of mercury, means for my hand this nineteenth day of January, breaking the continuity of said body of mer- 1911.

cury to strike an arc, and means for trans- ELII-IU THOMSON. 5 ferring discrete globules of mercury from Witnesses:

one of said reservoirs to the other while said J OHN A. MCMANUB, Jn,

are is operating. CHARLES A. BARNARD. 

